Nothing can take the place of common sense. Always attend your pressure cooker when it's in use, and read your user's guide before beginning.
The Duromatic pressure cookers by Kuhn Rikon represent a second generation of pressure cookers. These pressure cookers are built with safety features that prevent the problems sometimes seen with earlier cookers.
First, the automatic lid-locking device of the Duromatic pressure cookers insures that no pressure can be built up until the lid is on properly. It also insures that the lid cannot be removed or come off until all of the pressure has been released.
The Kuhn Rikon Duromatic cookers provide the ultimate in protection against excess pressure. The first indication that too much pressure has built up inside the cooker is the audible hiss of the valve as excess pressure is released through the valve (which is normally quiet.) When the user hears this, the heat should be turned down. As long as the valve is not clogged, it will relieve any over-pressurization by allowing steam to escape through the radial escape holes located on the valve stem.
Other safety releases will come into effect only if the central valve becomes clogged. If that occurs, excess pressure can also escape through the safety holes in the rim of the lid.
Additionally, another spring-loaded safety valve is set to release steam in the case of a clogged main valve due to overfilling or too-high heat. This valve is not a blow-plug like some old domestic cookers had, but a highly accurate spring-loaded valve which will open at a preset internal pressure and release steam safely and effectively.
Finally, at higher pressure, the gasket is forced out through the six bayonet flanges in the lid, and excess steam escapes in a downward direction